Difference between revisions of "Logit"

Revision as of 23:11, 21 January 2016

Logit(p)

The Logit function is equal to

[math]\displaystyle{ Logit(p) = \ln\left( p\over{1-p} \right) }[/math]

where [math]\displaystyle{ 0\lt p\lt 1 }[/math].

The inverse of the Logit function is Sigmoid(x) (before Analytica 4.5, the function InvLogit was used, defined in the 'Generalized Regression library). The logit function is sometimes called the log-odds function.

Library

Advanced Math Functions

Complex numbers

When p < 0 or p > 1, a warning is issued and if the warning is ignored, the result is NaN. This is the case unless you have enabled complex numbers. If you have set the system variable EnableComplexNumbers to 1, then no warning is issued and Logit(p) returns a complex number.

History

Logit was introduced as a built-in function in Analytica 4.5. Before that, it was supplied as a function in the Generalized Regression library.

@@ Line 3: / Line 3: @@
 [[Category:Doc Status D]] <!-- For Lumina use, do not change -->
-''Built-in function new to [[Analytica 4.5]].  Before that, supplied as a function in the '''Generalized Regression''' library.''
 == Logit(p) ==
@@ Line 13: / Line 12: @@
 :[[image:logitGraph.png]]
-The inverse of the [[Logit]] function is <code>[[Sigmoid]](x)</code> (before [[Analytica 4.5]], the function [[InvLogit]] was used, defined in the '''Generalized Regression'' library). The logit function is sometimes called the log-odds function.
+The inverse of the [[Logit]] function is [[Sigmoid]](x) (before [[Analytica 4.5]], the function [[InvLogit]] was used, defined in the '''Generalized Regression'' library). The logit function is sometimes called the log-odds function.
 == Library ==
@@ Line 22: / Line 21: @@
 When ''p < 0'' or ''p > 1'', a warning is issued and if the warning is ignored, the result is [[NaN]].  This is the case unless you have [[EnableComplexNumbers|enabled complex numbers]].  If you have set the system variable [[EnableComplexNumbers]] to 1, then no warning is issued and [[Logit]](p) returns a complex number.
+==History==
+[[Logit]] was introduced as a built-in function in [[Analytica 4.5]].  Before that, it was supplied as a function in the ''Generalized Regression'' library.
 == See Also ==
 * [[Sigmoid]](x)
 * [[LogisticRegression]]